238 
Fishery Bulletin 106(3) 
Table 2 
Mean length and standard deviation for each cohort of embryos during each sampling period for the Alaska skate (Bathyraja 
parmifera) at the eastern Bering Sea nursery site. A linear regression equation and growth rate for each cohort was estimated 
from mean embryo lengths. Number of embryos included in each mean length (±1 standard deviation) is denoted by n. The time 
lag between cohorts is the estimated interval between the cohorts — a period determined from mean cohort lengths and growth 
rates at each sampling period. Cohort 3 had hatched by 18 April 2005 sampling. 
Cohort 1 
Cohort 2 
Cohort 3 
Sampling period 
mean length (mm) 
n 
mean length (mm) 
n 
mean length (mm) 
n 
3 June 2004 
41.6 ±8.09 
20 
91.5 ±15.12 
10 
187.89 ±7.88 
9 
27 July 2004 
46.96 ±10.43 
23 
118.13 ±16.76 
8 
199.53 ±8.86 
15 
11 September 2004 
57.44 ±8.13 
73 
131.89 ±12.97 
46 
207.82 ±9.57 
11 
17 November 2004 
65.24 ±10.33 
53 
141 ±1.41 
2 
217 ±12.28 
8 
16 January 2005 
84.17 ±6.19 
18 
156.38 ±13.31 
21 
233 ±11.31 
2 
18 April 2005 
97.11 ±7.25 
28 
171.85 ±18.75 
13 
Hatching 
1 June 2005 
113.83 ±10.25 
24 
193.27 ±7.92 
27 
7 July 2005 
116.07 ±11.45 
57 
200.5 ±0.71 
7 
Linear equation 
y=0.1819x+13.40 
y=0.2214x+68.17 
y=0.1899x+ 158.80 
Growth rate of cohort 
0.18 mm/day 
0.22 mm/day 
0.19 mm/day 
Average growth rate 
0.20 ±0.02 mm/day 
Time lag between cohort 1 and 2 
348.79 ±41.27 days 
Time lag between cohort 2 and 3 
411.07 ±44.28 days 
TL was estimated. The time lag between cohorts 1 and 
2 was mean=348 ±41 days and between cohorts 2 and 
3 mean=411 ±44 days and an overall mean=371 ±50 
days between egg deposition events of cohorts one, two, 
and three combined (Table 2). These data indicate an 
annual egg deposition cycle, and each cohort represents 
the result of a single reproductive event that occurs 
during the summer months. 
